Self-luminous reticle



Patented Dec. 6, 1949' UNITED STATES ITENT OFFICE SELF-LUMINOUS RETICLE Robert E. Reardon, Camden, N. J. Application February 14., 1945, serial No. 577,828

(Cl. Z50-71) (Granted 'under the act of March 3, 1883, as

1 Claim.

My invention relates to reticles for optical in struments and it has special reference to selfilluminated reticles.

One object of my invention is to provide a reticle which is entirely self-luminous.

Another object is to protect the reticles face.

from injury.

`A further object is to avoid obscuration of vision in optical instruments by light haze or glare in the reticle body caused by the illuminating means. Reticle units constructed in accordance with my invention utilize a reticle element which constitutes one end of an evacuated box or hollow disc. The reticle grooves are exposed to the vacuum within the box and are illled with a fluorescent substance. Such substance is made visible by radiation from a radio-active substance that is incorporated in a glow ring which denes the units periphery. In this way I provide a self-luminous reticle unit which is independent of natural lighting conditions.

One preferred form of my improved reticle unit is shown by the accompanying drawings wherein:

Fig. 1 is a view in side elevation partly in section of the assembled unit containing the glass e plate on'which the reticle lines are formed;

Fig. 2 is a vertical section view of the Fig. 1 unit showing the units glow ring and other features of internal construction;

' Fig. 3 is a sectional plan view taken on line 3--3 of Fig. 1 showing further details of the glow ring;

Fig. 4 is an enlarged section on line 4-4 of Fig. 3 showing iluorescent material dllling a reticle groove;

Fig. 5 is aside elevation view of the assembled reticle unit showing one manner by which the glow ring may be cemented to the unit's window;

Fig.V 6 is a partial sectional view of a reticle unit having additional ray protective and concentrating means;

Fig. 7 is a top plan view of a vacuum chamber (with the cover removed) useful ln manufacturing my improved reticle units shown therein as awaiting vacuumizing and iinal assembly;

Fig. 8 is a view in lengthwisevertical section through the chamber of Fig. '7 showing evacuating and heating apparatus associated therewith;

and

amended April 30, 1928; 370 0. G. 757) Fig. 9 is an enlarged vertical section taken along line 9-9 of Fig. 7 showing further details of the reticle unit assembling mechanism and process.

My improved self-luminous reticle unit which comprises a cylindrical box having transparent end faces I4 and I5, the latter being shown as a reticle disk. These end faces are spaced by a hollow ring I6 which may have a cross-sectional shape as clearly shown at Figure 2. The ring has openings I8 through its side Wall lc'adjacent face I5 and through which openings it may be filled with a radio-active substance I1.

Reticle grooves I9, Figure 3, may be cut or etched into the inner surface of disc I5 and filled with a fluorescent substance 20. This substance is caused to fluoresce by the radio-active substance I'l so that the reticle lines I9 stand out `prominently to an observer looking through the telescope or other optical instrument.

In the construction shown, the window I4 and the reticle face I5a. are preferably secured to their respective sides of the glow ring I6 by an opaque cement 24 (see Figs. 2 and 5).

In order to obtain maximum benefits of the radio-active substance I1 a coating of silver or graphite 2|, Figure 6, may be applied to the internal surface of ring I6 to thereby reect rays incident therein and increase the emanation eiective upon uorescent material 2U.

The external sides of these same walls IBb--I Ec-I 6d are preferably covered with a substance 23 such as lead which resists transmission of the rays, and thus adds to the effect of the interior lining in concentrating the rays upon the fluorescent material 20.

Shielding of the observers eyes from excessive radio-activity may be completed by use of a material similarly impervious to such rays on the outer margin of the window I 4 and reticle disc I5, as best shown at 25 in Fig. 6.

To achieve the full benets of my novel reticle unit, a high vacuum is maintained within the unit for reasons later to be explained.

One such reticle unit as has just been described is illustratively shown in Fig. 1 as mounted in a section of a typical optical instrument comprising a tubular casing 22 in which the line of sight passes through the reticle.

Various known radio-active compounds Il which may be used to supply the invisible rays that cause the groove markings ller 2|) to fluoresce may be used. Among these are a mixture oi' radium andzinc sulfide. The fluorescent illler 2 0 may be any commercially available substance having the desired uorescing properties, such as calcium tungstate, or oxides of titanium, zinc, barium or lead mixed with small amounts of scdium naphthionate, or eosin anthracene, or fluorescein, or other such materials.

Method of making reticle unit To accomplish the various objects of my improvements, the vacuum :box-like or hollow disc unit which I have described may be constructed ln a number of ways. One preferred method is illustratively shown in Figs. 5, 7-8-9.

In order to maintain indefinitelyr a high vacuum within a reticle, the component parts of my reticle unit must be joined togtherf'with an air-tight seal. Any suitable cement 24.preferably opaque, capable of making such a'seal between glass or plastic parts lis-'^satisfactory for this purpose. Y

By means of such cement 24, the reticle disc lilr is permanently'attaohedto the glow ring I6 ,which is first filled with the radio-active substance l1 through the openings l8.(see Figs. 3, 9). The manner of cementing the reticle discwlliv to vthe glow ring I6 is such thatthe groove markings I9on the recticleface l5a will face the inside of the completed box. `This-partially assembledrunit isplaced upon a serrated ring-of the `sealing cement 24jwhich covers the peripheral margin of the window I4, las shown in Fig. 5. The reticle 'conventional operation of'l vacuumizing means shown schematically at YSfSfill iny Fig., ,8. Such exhaustion is continued until the chambers pinternallpressure `has beenfso,l reduced to cause an adequate vacuum therein.l

' j the air is withdrawn ,from theichamberlll it., .isvlikewise exhausted Afromthe ,reticle .units vsituated therein Vby passage through spaces .be-

tween the serrated .ridge `of sealing. cement. 24 (,sereFigs. 5 and'9) andthe glow ring lresrting thereon Suchspas. result ,fromme originel ,Serretedf placement of the. .cement ,on the, gur- 'face of.wi ndow vi4 in'fits hardened or room-temperature condition. ,f Y ,s y, u

4When a satisfactory "ghvacuum hasbeenlobtained'. heat isY applied tothe basepr'chamber 2,6 in any suitable manner as -bythe aid ofY an electriofgrd'or hot plate schematically indicated means1 also may be'emplo'yed, should greater rapidity be desired, Y v A 1 i K softening oi the serratedY cement A24 Yis vthus efected, permitting the glowfring 1 6 withat'- tachedfreticle disc l5 to settle down on the windew 44. l on'cessationuof heating, gement 24 liardens Aand eiectively'seals and'cmpletesftlie unit.

A One means of properly lining up the window I4 with the glow ring i6 and reticle disc l5 as they are being joined together is to use three or more alignment pins 36. These pins 36 are Yalixed to the base of chamber 26 at substantially equidistances around the circumference of a s circle having the same diameter as that 'of each reticle unit being processed. Each unit is placed within the area bordered by these pins to maintain the desired alignment as the joining process is being carried on.

The inner wall I6a (again see Fig. 6) of the glow ring may take the form of a glass filter of the type which transmits'only infra-red rays and eliminates visible light which would cause glare or haze .before the observers eyes. Such a lter `may be made of glass containing oxides of iron or manganese. If ultra-violet rays be desired, a filter appropriate for the transmission thereof maybe substituted.

Optionally the glow ring I6 may be constructed of plastic material instead of glass. Cellophane, for example, transmits invisible infra-red rays almost as well as quartz, which is well known to be highly 'transmissive of these rays. Several plastics now commercially available are capable of high ultra-violet transmission, too.

By a process well known to the optical engineering art, such plastics may be treated so as to be entirely opaque to such light, while leaving the untreated inner side wall Ia still capable of transmitting the desired rays. 1 ,As previously mentioned, special coatings may be applied to the walls of the glow ring I6 as shown at 23, and around the outer margins of the complete reticle unit, as shown at 25, to concentrate the radiative effect of the radium substance Il toward the reticle markings I9. Fig. 6 clearly shows how the lead or other ray-resisting material 25 acts to prevent ray loss to the outside of the unit.

Additional protection is aiorded by the similar substance 23 applied to the external sides of glow ring walls |6b-I6c-I6d. To help reflect the rays and concentrate the rays through the selective ray lter constituting the wall Ilia, an internal wall lining may be applied, such as silver or graphitized carbon, as indicated at 2|.

The amount of radio-active compound Il used in the glow ring must of course be dependent upon the size of the optical instrument in which my improved reticle unit is to be used, which factor will, in turn, regulate the size of the unit itself. It is desirable to contain a suflicient bulk of radio-active substance Il in the glow ring IB so that the luminescent-life will cover a period of years.

I claim:

In a hollow, cylindrical,v self-luminous, selfcontained reticle cell for an optical instrument, a hollow toroidal ring generally rectangular in axial diametrical cross section, rst and second circular transparent plates of substantially the same diameter as said ring and secured to respective sides of said ring in air-tight relation therewith, there being reticle grooves formed upon theinner face of said rst plate, fluorescent material lling said grooves, a radio-active substance fillingY the toroidal chamber of .said ring,

Va lining of silver extending over the inside sur.

Boissier1 E. REARDON.

{References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 5 Number Name Date 804,624 Saegmuller Nov. 14, 1905 863,287 Kunz Aug. 13, 1907 1,272,326 Barr et a1. July 9, 1918 Friedrich Apr.29,1919 1 Number 

